Engineering a Heterostructured Cu₂S/NiS₂/C Composite as a Secondary Battery Anode Displaying Long Cycle Life and Stable Temperature Tolerance

Currently, nonideal anode materials restrict the applications of sodium-ion (Na-ion) batteries, while heterostructured composites would be potential candidates. Here, we develop a Cu2S/NiS2/C heterostructure as a high-performance anode applicable for wide cycling conditions. The heterogeneous structure is able to improve Na+ ion diffusion and reaction kinetics, and the interconnected nanosheet morphology is conducive to exposing active sites for reactions and alleviating the volume change during cycling, thus enabling enhanced electrochemical performances. In situ X-ray diffraction patterns demonstrate a reversible phase change upon cycling. The Cu2S/NiS2/C anode displays a stable capacity of 318 mA h g–1 after 2200 cycles at 1 A g–1, along with a Coulombic efficiency exceeding 99%. When cycling at 0.1 A g–1, the capacity reaches 491 mA h g–1, which significantly exceeds those of many reported anodes. Moreover, it exhibits good temperature tolerance with capacities of 508 mA h g–1 after 500 cycles at 1 A g–1 under 50 °C and 383 mA h g–1 after 50 cycles at 0.1 A g–1 under −10 °C, which are much better compared to those of Cu2S/C and NiS2/C without heterostructure. In addition, good full-cell performance is also achievable. Those findings enable the heterostructured design and general preparation approach to be broadly used for developing high-performance energy-storage systems.